1. Field of the Invention
The present invention relates to gas turbine power plants, and more particularly to gas turbines of the compressor-combustor-turbine configuration conformed for minimal geometry.
2. Description of the Prior Art
The use of of a turbocompressor cycle to generate power has been extensively practiced in the past, and the modern jet engine is one illustrative example thereof. The cycle, sometimes referred to as the Brayton cycle, is characterised by adiabatic compression, constant pressure heating and thereafter adiabatic expansion of the heated, compressed gas that includes the heat of combustion. The net power output is then realised through a turbine driven by the expanding gas, and the power plant is therefore known as a gas turbine power plant.
The theoretical cycle efficiency of the Brayton cycle is defined as a ratio of the net energy in excess of that required for compression, divided by the energy added during combustion. Stated otherwise, the thermal efficiency of the cycle is determined mainly by the compressor pressure ratio and the turbine inlet temperature, and it is these two parameters that govern the design of the power plant. Of these two the implementation of the compressor has followed various combinations of two basic physical paths, those obtaining compression by centrifugal effects and those compressing gas through axial stages. Thus the generic types of compressor assembly are known as centrifugal, axial or mixed configurations.
Turbine inlet temperature, in turn, is ultimately a function of material selection and cooling design. While this aspect presents the more formidable engineering task, the inherent limits of a stationary combustion chamber result in pressure-to-temperature exchange and the losses incident thereto. The same centrifugal placement of combustors greatly simplifies the over-all structure since the combustor may form one part of a rotary device. The compressor, combustor and turbine may thus form an integral structure.
In this manner design simplicity can therefore be obtained by conserving the centrifugal pressure in the combustor, and it is one such configuration that is disclosed herein. The same centrifugal placements of combustors allow for further simplification in the design, obtaining packing convenience associated therewith and the incident reduction in mass and complexity. Thus several advantages are obtained, resulting in a power plant that is simple in design, convenient in fabrication and reliable in use.